In the prior art, in order to learn about indoor activity information (generally of a person), a human body generally needs to wear a sensing device, or a video monitoring device is generally used.
The sensing device is normally usable only when the sensing device is worn on the human body, which is relatively troublesome; and the monitoring device tends to cause leakage of personal privacy in daily life, and is complicated in recognizing and calculating, and is currently unsuitable for commercial application.